ul.tree{margin:5px;list-style-type:none}
ul.tree ul{display:none;margin-left:5px;list-style-type:none}
ul.tree li{padding-left:12px;margin:2px 0}
ul.tree li.sub{background-image:url(../img/tree_closed.png);background-repeat:no-repeat;background-position:3px 4px}
ul.tree li.sub.opened{background-image:url(../img/tree_opened.png);background-position:0 4px}
ul.tree a{display:block;padding:2px 4px;text-decoration:none;color:#555}